Robust organic radical molecular junctions using acetylene terminated groups for C-Au bond formation

TL;DR

This paper introduces a new organic radical with acetylene groups that forms stable, reproducible covalent bonds with gold electrodes, improving the reliability of molecular electronic devices.

Contribution

It reports the synthesis and characterization of a radical molecule with alkyne groups for robust C-Au bond formation, enhancing device stability and reproducibility.

Findings

C-Au bonds are more stable than sulfur-based linkers.

Self-assembled monolayers show high stability at room temperature.

Quantum calculations confirm reduced conductance variability.

Abstract

Organic paramagnetic and electroactive molecules are attracting interest as core components of molecular electronic and spintronic devices. Currently, further progress is hindered by the modest stability and reproducibility of the molecule/electrode contact. We report the synthesis of a persistent organic radical bearing one and two terminal alkyne groups to form Au-C {\sigma} bonds. The formation and stability of self-assembled monolayers and the electron transport through single-molecule junctions at room temperature have been studied. The combined analysis of both systems demonstrates that this linker forms a robust covalent bond with gold and a better-defined contact when compared to traditional sulfur-based linkers. Density functional theory and quantum transport calculations support the experimental observation highlighting a reduced variability of conductance values for the C-Au based junction. Our findings advance the quest for robustness and reproducibility of devices based on electroactive molecules.